2. Main Idea and New Vocabulary Key Concept: Probability
Example 1: Find Probability
Example 2: Real-World Example
Example 3: Complementary Events
Lesson Menu

3. Find the probability of a simple event.
outcome
simple event
probability
random
complementary event
Main Idea/Vocabulary

4. Key Concept

5. Answer: The probability of the spinner landing on a 3 or 4 is , or
Find Probability
If the spinner shown is spun once, what is the probability of it landing on a 3 or a 4?
Answer: The probability of the spinner landing on a 3 or 4 is , or
Example 1

6. What is the probability of rolling an odd number on a number cube marked with 1, 2, 3, 4, 5 and 6 on its faces? A. B. C. D.
Example 1 CYP

7. The possible outcomes of spinning the spinner are 1, 2, 3, 4, 5 and 6.
GAMES A game requires spinning the spinner that is shown. If the number spun is less than 5, the player wins. What is the probability of winning the game?
The possible outcomes of spinning the spinner are 1, 2, 3, 4, 5 and 6.
In order to win, the player would need to spin a 1, 2, 3, or 4.
Example 2

8. Let P(A) be the probability of winning the game.
There are 6 possible outcomes, and 4 of them are favorable.
Answer: The probability that the player will win is or about 66%.
Example 2

9. CHORES George and Ashton decided to roll an 6-sided number cube with numbers 1–6 on its faces to determine who would take out the garbage. The person who rolls a 1 or a 4 first wins and does not have to take out the garbage. What is the probability of winning? A. B. C. D.
Example 2 CYP

10. Complementary Events
GAMES A game requires spinning the spinner shown below. If the number spun is less than 5, the player wins. What is the probability of not winning the game?
Example 3

11. P(A) + P(not A) = 1 Definition of complementary events
+ P(not A) = 1 Replace P(A) with .
Subtract from each side.
is or
Answer: The probability that the player will not win is or about 33%.
Example 3

12. CHORES George and Ashton decided to roll an 6-sided number cube with numbers 1–6 on its faces to determine who would take out the garbage. The person who rolls a 1 or a 4 first wins and does not have to take out the garbage. What is the probability of not winning? A. B. C. D.
Example 3 CYP